This invention relates generally to deflection systems for kinescopes and particularly to enhanced horizontal deflection for such devices.
Kinescopes typically include a funnel shaped evacuated envelope with the wide end closed by a light transparent faceplate. The inside of the faceplate is coated with one or more phosphor materials which luminesce when struck by electrons. A neck portion is attached to the narrow end of the funnel and houses an electron gun. The electron gun provides the electrons which travel as beams to the phosphor on the faceplate to produce a visual output which is either color or black and white depending upon the number of electron beams and phosphors on the faceplate. A deflection system is used to horizontally and vertically deflect the electron beams so that the entire faceplate is scanned by the electron beams. Typically, the deflection system includes a magnetic yoke positioned around the exterior of the tube neck.
The horizontal deflection angle of a kinescope is the total angular deflection of the electron beam away from both sides of the center line of the envelope. This angle varies in accordance with the strength of the magnetic field which causes the deflection and thus is a function of the voltage applied to the deflection coil. Therefore, the deflection angle can be increased by increasing the deflection voltage, this constitutes an increase in the power consumption and thus is inconsistent with efforts to increase the efficiency of kinescopes. Accordingly, in the absence of an increase in deflection voltage, an increase in the size of the faceplate requires an increase in the distance between the electron gun and the faceplate. This requires an increase in the overall length of the tube and thus is objectionable. Additionally, efforts today are directed toward decreasing both the power consumption and overall tube length. Efforts directed to both of these considerations have been unsuccessful because of the inability to increase the deflection angle without increasing one of the parameters which preferably should be decreased. These considerations have also caused the failure of efforts to construct a thin kinescope, that is a kinescope which is in the order of 6 inches (15.25 cm) in total length.
The instant invention is directed to a deflection enhancement device for enhancing the horizontal deflection of a kinescope without increasing the power requirements thereby permitting a substantial decrease in the overall length of the tube.